St. Patrick's Day is celebrated worldwide by the Irish and those of Irish descent. A major parade takes place in Dublin and in most other Irish towns and villages. The three largest parades of recent years have been held in Dublin, New York and Birmingham England. Parades also take place in other centres, London, Paris, Rome, Moscow, Beijing, Hong Kong, Singapore and throughout the Americas. The first civic and public celebrations of St. Patrick's Day in the American Colonies took place in Boston in 1737. The first St. Patrick's Day celebrated in New York City was held at the Crown and Thistle Tavern on March 17, 1756. Since then the New York celebration has become the largest St. Patrick's Day Parade in the world (see external link). The parade dates back to 1762, and in 2003 more than 150,000 marchers (bands, military and police groups, county associations, emigrant societies, social and cultural clubs etc.) participated. It has however been dogged with controversy in recent years; its organisers banned Irish gays and lesbians from marching as a group - an act which has led to calls in Ireland (which, since 1992 has some of the most liberal gay laws in the world) for its boycotting. On occasion the Ancient Order of Hibernians (http://mill-valley.freemasonry.biz/marin_hibernians_orangemen_royal_black_knights.htm) has appointed controversial Irish Republican figures (some of whom were barred from the US) to be its Grand Marshal. The longest running St. Patrick's Day parade in Canada takes place in Montreal. The 2003 parade was the 179th - the first Montreal parade taking place in 1824. Paradoxically, St. Patrick's Day parades in Ireland date from the late 19th century, originating in the growing sense of nationalism of the period. Some US cities also paint the traffic stripe of their parade routes green; other US cities, including Chicago, also dye their main rivers 'green', an act that most native Irish people find bizarre.

Since the 1980s, Irish taoisigh (prime ministers) have attended special functions either on St. Patrick's Day or a day or two earlier, in the White House, where they present shamrock to the President of the United States. A similar presentation is made to the Speaker of the House. Originally only representatives of the Republic of Ireland attended, but since the mid - 1990s all major Irish political parties from north and south are invited, with the attendance including the representatives of the Irish government, the Ulster Unionists, the Social Democratic and Labour Party, Sinn Féin and others. In recent years it is common for the entire Irish Government to be abroad representing the country in various parts of the world. In 2003, the President of Ireland celebrated the holiday in Sydney, the Taoiseach (Prime Minister) was in Washington, while other Irish government members attended ceremonies in New York, Boston, San Francisco, San Jose, Savannah, Chicago, Philadelphia, San Diego, New Zealand, Hong Kong, South Africa, Korea, Japan and Brazil.

In Britain, the late Queen Elizabeth, the Queen Mother used to present bowls of shamrock specially flown over from Ireland to members of the Irish Guards, a regiment in the British Army made up of Irish people from both Northern Ireland and the Republic of Ireland.

In many parts of the United States and Australia, expatriate Irish, those of Irish descent, and ever-growing crowds of people with no Irish connections but who proclaim themselves 'Irish for a day' also celebrate St. Patrick's Day, usually by consuming large quantities of Irish beer (sometimes dyed green as well), such as Murphys, Smithwicks, Harp or Guinness or other Irish liquors such as Irish whiskey, Irish Coffee or Baileys Irish Cream, and listening to Irish folk music. (Former New York mayor Ed Koch once proclaimed himself 'Ed O'Koch' for the day!)